One of the most significant advantages that modern cameras have over their film-based counterparts of days gone, by is their ability to change how sensitive they are to light with the touch of a button.
Back in the days of film you had to decide ahead of time whether you wanted to shoot at ISO (then called ASA) 100, 200, 400, or in extreme cases, 800. If you were going to take pictures outdoors, a roll of 24 or 36 exposure, 100 or 200 film would work fine, but woe betide the... more